Broach



July 23, 1946. L. 1. KAPLAN U AL BROAGH Filed March 22, 1938 77 p Km P0:I 473 1 44 INVENTOR.

ATTORNEY.

Patented July 23, 1940 UNlTED STATES PATENT oFFicE BROAOH Leo I. Kaplan'and Bror Gustaf von Reis, Detroit,

Mich., assignors to Detroit Broach Company, a corporation of MichiganApplication March 22, 1938, Serial No. 197,443 Claims. (01. 29-951) Thebroach herein revealed is of a type gen erally similar to that describedin my copending application Serial No. 195,673, filed March 14, 10 1938.It differs therefrom in the manner of cutter staging, it having beenfound that the tool may be shortened by altering the stages as to thosecutters having the function of forming the arcuate corners of therectangle.

Also, it is recognized that a broach will often leave its course andthereby cutv an imperfect formation. It is an object of this inventionto provide. a broach with guide means therefor active throughout itslength;

More particularly it is. an object to provide a broach having guidesurfaces at each cutter, these surfaces changing along the length ofthebroach.

. Another object of this invention is to provide a multiple stage broachfor forming agroove, one stage having dual cutters in the grooveandancutting edges of each dual cutter being normal to each other and.each single cutter having arcuate cutting edges in continuation of thecuts begun by the dual cutters. j

A further object is to provide a broach for cutting groups of internalsplines circumferentially spaced and separated by arcuate bearingsurfaces, the cutters being arranged in stages in such manner that thesplines are completely cut simultaneously with starting the initial cutsof the bearing surfaces. The cutters thereafter being relieved of allduties except that of finishing the bearing surfaces.

Other objects and advantages willbecome more fully apparent as referenceis had to the accompanying drawing wherein my invention is illus-.trated, and in which, f

Fig. 1 is a side elevation of my improvedbroach.

Fig. 2 is a transverse section taken along the line 2-2 of Fig. 1,

Figs. 3 and 4 are transverse sections taken along the lines 33 and 44respectively of Fig. 1, showing the spline and bearing surfaceformationrespectively.

More particularly, 1 indicates a Work piece in the interior walls ofwhich it is desired to form internal splines and bearing surfaces.- Thepiece I is generally of cylindrical exterior and is origiother stagehaving single finishing cutters, the

nally of cylindrical interior shape and machined or otherwise preferablyformed into a rectangular shape with rounded corners as indicated by thedotted lines 2. The broach herein provided enlarges the opening 2 to thefinal form indicated by the dotted lines 3.

The broach, as illustrated in r Fig. 1, is composed of threelongitudinally spaced stages of cutters, the section of Fig. 2 beingtaken at the final cutter of the first stage and the sections of Figs. 3

and 4 being taken at the first cutter of the second and third stage,respectively. A section 4 at the smallest end of the broach has a slot 5therein for attachment of the broach to a machine by which it may bepulled or pushed through the work piece either vertically orhorizontally. Between the section 4 and the first cutter 6 is a section1 which is rectangular in cross section, and which guides the firstcutter 6 to its cutting position.

The cutters of the first stage are all rectangular H mended that thecutters 6 be true rectangles with a sharp corners thus cutting away thestock of the corners of the opening 2. It is recommended that the hole 2be accurately centered before broaching. The corner portions I4 thenhave no other function than to guide. The cutters 6 of the first stagehave straight sidewalls and continue to take cuts until the opening 2has reached the surfaces of the splines l to be cut as shown in Fig. 2.

The splines 1 are herein illustrated as being five in number along eachside of the rectangle, each set of five splines being considered a groupwhich is peripherally spaced from each adjacent group by a distancegreater than the width of a spline. The first cutter 8 of the secondstage of cutters has a plurality of shallow grooves or cut out portions9 along eachside thereof thus forming a plurality of cutting edges, andbegins to form all of these splines 1 simultaneously, each succeedingcutter in this stage taking a progressively deeper cut as illustrated inFig. 3 until all splines are completely formed. The outside surfaces ofthe end splines of each group are only partially formed in this stage,the cutting edges In therefor being progressively narrower andterminating before a groove depth equal to that of the splines are out.These cutting edges are each parallel to the other spline formingcutting edges so that two of these edges It normal to each other arecutting out each of the portions circumferentially separating the groupsofsplines simultaneously with spline formation. The corner surfaces l4separate the corner cutters Hi into pairs, or into dual cutters, andcontinue to serve no other purpose than guides during cutting by thissecond stage, also.

The first cutter l l of the final stage of the cutters has four arcuatecutting edges l2, which grow progressively larger as illustrated in Fig.4. Separating the arcuate cutters are grooves l3 which accommodate thesplines l which have been completely formed. The grooves it nowcooperate with the splines" to'constitute guides while the corners arebeing out. The cutting edges i2 complete the cutting of the portions separating the groups of splines, the portions thus out into the member Iconstituting bearing surfaces for engagement with similar surfaces of amale member (not shown) in order to relieve the splines of all butdriving functions.

What is claimed is:

1. A broach comprising a plurality of longitudinally spaced stages ofcutters with the cutters of each stage having a contour similar to thatof the other cutters in the same stage and different from that of anyother stage, the stages and the cutters of each stage progressivelyincreasing in size from front to rear of the broach, the cutters of thefirst stage all being substantially rectangular, the cutters of thesecond stage being rectangular and having a plurality of spline forminggrooves in each side thereof, the cutting surfaces of the lands on eachside of said grooves of any cutter being coplanar throughout any side ofthe rectangle, the cutters of said third stage being rectangular andhaving spline accommodating grooves separated by non-cutting landsformed in each side thereof, said sides being connected by arcuatecutters of progressively increasing size, the arcuate cutters on thefinal cutter of the ,last stage being at a greater distance from thecenter of the rectangle than any portion of any of said lands orgrooves.

2. A male broach comprising a broach body having a plurality of enlargedportions regularly spaced along the major portion of the length thereof,each of said portions comprising peripherally spaced cutting edgesseparated by non-cutting surfaces, said non-cutting surfacesconstituting guides for said cutting edges, said noncutting surfacesshifting their angular position between the first and last of saidportions.

3. A male broach comprising a broach body having enlarged portionsregularly spaced along the major portion of the length thereof, a partof the periphery of each of said portions constituting a cutting edge,the remainder of each of said portions constituting guiding means, saidcutting edges increasing in diameterfrom portion to portion, saidguiding means being of constant radius from portion to portion, thatpart of said peripheries constituting cutting edges for some of saidportions becomin guide surfaces for others of said portions, that partof said peripheries constituting guide surfaces becoming cutting edgesupon the adjacent parts becoming guide surfaces whereby all of saidportions comprise guide means and cutting edges.

4. A male broach for formingan opening in a work piece to provide groupsof splines separated circumferentially by bearing surfaces, said broachhaving cutters for forming the splines, and cutters for forming thebearing surfaces, the cutters for forming each bearing surfacecomprising a first series of cutters of progressively increasing size,each cutter of said first series being composed of cutting edgesarranged in pairs with the edges of each pair at right angles to eachother, and a second series of cutters longitudinally behind the firstseries and also of progressively increasing size, each of the last namedcutters being arcuate and of a circumferential extent equal to that ofthe bearing surface to be formed, the arcuate cutters of the secondseries being aligned with the pairs of cutters of the first series.

5. A male broach for forming an opening in a work piece to providegroups of splines separated circumferentially by bearing surfaces, saidbroach having cutters for forming the splines and cutters for formingthe bearing surfaces, the cutters for forming each bearing surfacecomprising a series composed of a plurality of aligned pairs of cutterswith the cutters of each of said pairs normal to each other, said pairsof cutters pregressively increasing in size from front to rear of thebroach, and a second series of aligned arcuate cutters aligned with saidpairs, the cutters of said second series progressively casing in size,the final one of said second series ha ing a peripheral portion equal tothe width of the bearing surface being cut.

6. A male broach for forming a plurality of groups of splines separatedcircumferentially by bearing surfaces having arcuate bases and a commoncenter of curvature, said broach having cutters for forming the splinesand cutters for forming the bearing surfaces, the cutters for formingeach bearing surface comprising a first longitudinal series of cuttersof progressively in" creasing size, each cutter of said series beingcomposed of spaced sets of two cutting edges, thecutting edges in eachof said sets being normal to each other, and a second series of cuttershaving cutting edges of arcuate shape, said arcuate cutting edges eachcontinuing the cuts started jointly by the sets of cutting edges of thefirst series.

'7. A male broach for forming an opening having splines separatedcircumferentially by hearing surfaces, said broach having a series ofspaced parallel cutting edges for forming the splines and non-cuttingsurfaces between certain of said cutting edges, said surfacesconstituting guide means for said cutting edges during formaticn of thesplines, and cutting edges for completing the formation of said bearingsurfaces subsequent to the formation of the splines.

8. A male broach for forming an opening having splines separatedcircurnierentially by bearing surfaces, said broach having a series ofspaced parallel cutting edges for forming the splines and non-cuttingsurfaces between certain of said cutting edges, said surfaces constituti1g guide means for said cutting edges during formation of the splines,cutting edges for completing the formation of said bearing surfacessubsequent to the formation of the splines, and guide surfaces on saidbroach adapted to coact with the formed splines for guiding the broachduring the formation of said bearing surfaces.

9. A male broach having cutters for forming a rectangular hole withsplines in the sides thereof and bearing surfaces at the corners, saidbroach having guide means coacting with the corner surfaces of the holefor guiding the breach during formation of the splines, and meanscoacting 2,209,026 n 3 with surfaces of said hcle after formation of thesplines, and means for guiding the breach during formation of saidbearing surfaces. I

10. A male broach having cutters for forming a rectangular hole withsplines in the sides thereof and bearing surfaces at the corners, saidbroach having guide means coacting with the corner surfaces of the holefor guiding the broach during formation of the splines, and non-cuttingsurfaces for engaging the formed. splines for guiding said breach Whilethe bearing surface cutters are operative.

BROR GUSTAF VON REIS. LEO I. KAPLAN.

